By default, LVM2 does not consider device-mapper block devices.
To enable the multipath I/O devices for LVM2, change the device section of /etc/lvm/lvm.conf as follows:
With the preceding settings, you should be able to use the multipath I/O devices for LVM2. The next steps are similar for all types of block devices.
The following example shows the steps to create a volume group that is composed of four multipath I/O devices. It assumes that the multipath I/O devices are already configured.
# multipath -l
36005076303ffc56200000000000010d2 dm-2 IBM,2107900
size=5.0G features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=-2 status=enabled
|- 0:0:24:1087520784 sdc 8:32 active undef running
`- 1:0:20:1087520784 sdg 8:96 active undef running
36005076303ffc56200000000000010d1 dm-1 IBM,2107900
size=5.0G features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=-2 status=enabled
|- 0:0:24:1087455248 sdb 8:16 active undef running
`- 1:0:20:1087455248 sdf 8:80 active undef running
36005076303ffc56200000000000010d0 dm-0 IBM,2107900
size=5.0G features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=-2 status=enabled
|- 0:0:24:1087389712 sda 8:0 active undef running
`- 1:0:20:1087389712 sde 8:64 active undef running
36005076303ffc56200000000000010d3 dm-3 IBM,2107900
size=5.0G features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=-2 status=enabled
|- 0:0:24:1087586320 sdd 8:48 active undef running
`- 1:0:20:1087586320 sdh 8:112 active undef running
# pvcreate /dev/mapper/36005076303ffc56200000000000010d0
Physical volume "/dev/mapper/36005076303ffc56200000000000010d0" successfully created
Repeat
this step for all multipath I/O devices that you intend to use for
LVM2.# vgcreate sample_vg /dev/mapper/36005076303ffc56200000000000010d[0123]
Volume group "sample_vg" successfully created
# vgdisplay sample_vg
--- Volume group ---
VG Name sample_vg
System ID
Format lvm2
Metadata Areas 4
Metadata Sequence No 1
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 0
Open LV 0
Max PV 0
Cur PV 4
Act PV 4
VG Size 19.98 GB
PE Size 4.00 MB
Total PE 5116
Alloc PE / Size 0 / 0
Free PE / Size 5116 / 19.98 GB
VG UUID Lmlgx9-2A2p-oZEP-CEH3-ZKqc-yTpY-IVOG6v
Now
you can proceed normally: Create logical volumes, build file systems,
and mount the logical volumes.When configured, the multipath I/O devices and LVM2 volume groups can be made available at start time. To do this, continue with the following additional steps.
# zipl
Using config file '/etc/zipl.conf'
Building bootmap in '/boot/zipl'
Adding IPL section 'ipl' (default)
Preparing boot device: dasda (2c1a).
Done.
SCSI subsystem initialized
...
scsi0 : zfcp
qdio: 0.0.181d ZFCP on SC 10 using AI:1 QEBSM:1 PCI:1 TDD:1 SIGA: W AO
scsi1 : zfcp
qdio: 0.0.191d ZFCP on SC 11 using AI:1 QEBSM:1 PCI:1 TDD:1 SIGA: W AO
...
device-mapper: uevent: version 1.0.3
device-mapper: ioctl: 4.16.0-ioctl (2009-11-05) initialised: dm-devel@redhat.com
device-mapper: multipath: version 1.1.1 loaded
device-mapper: multipath round-robin: version 1.0.0 loaded
device-mapper: multipath queue-length: version 0.1.0 loaded
device-mapper: multipath service-time: version 0.2.0 loaded
...
scsi 1:0:20:1087127568: Direct-Access IBM 2107900 .280 PQ: 0 ANSI: 5
scsi 1:0:20:1087127568: alua: supports implicit TPGS
scsi 1:0:20:1087127568: alua: port group 00 rel port 233
scsi 1:0:20:1087127568: alua: rtpg failed with 8000002
scsi 1:0:20:1087127568: alua: port group 00 state A supports tousNA
sd 1:0:20:1087127568: Attached scsi generic sg0 type 0
sd 1:0:20:1087127568: [sda] 10485760 512-byte logical blocks: (5.36 GB/5.00 GiB)
sd 1:0:20:1087127568: [sda] Write Protect is off
sd 1:0:20:1087127568: [sda] Mode Sense: ed 00 00 08
sd 1:0:20:1087127568: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
sda: unknown partition table
sd 1:0:20:1087127568: [sda] Attached SCSI disk